Acoustic diaphragm



Devn 25, 1928. 1,696,565

C. lBLIEBERGER Acousmq DIAPHRVAGM Fi1d'sept-4, 1926 INVENTR maker Patented Dec. Z5, 1928.`

UNITED s'T TES PATENT OFFICE.

CHARLES BLIEBRGER, 01Ev NEWr YORK, N. Y;

ACOUSTIC DIAPHRAGM.

roducinr sound the diaphragm is actuated y lsuitab e means (usually mchanicalor electrical) in accordance with the sound to beA replroduced and the diaphragm sets -up the necessary waves in the airvto produce the 'desired sound. The action of `the diaphragm in tle'two cases is analogous, as is Well understood in the art; and for the sa'ke of simplicity the following disclosure will refer primarily to the action of the diaphragm in 'A reproducing sound. Itis to be understood,

however, that the diaphragm may be used eitherfor reproduction or recording.

The conventional diaphragm responds more readily to' certain frequencies than it does to others. Both music and speech consist of a wide range of frequencies and for faithful reproduction the diaphragm must vibrate at any given frequency with a volume corresponding to the volume of that frequency in the original sound. Otherwise, that frequency will be either accentuated or diminished in the reproduced sound, thus causing distortion. Various expedients have been resorted to in an attempt to cause a diaphragm to give a volume of vibration at any particular frequency which will correspond with, the volume of that frequency naturally present in the sound being dealt with. However, the expedients have been only partly successful, with the result that the diaphragm'has always caused an objectionable amount of distortion in the recording and reproduction of sounds.

The general object of the present invention is to. provide an acoustic diafphragm which will respond to the various requericies present in speech and music with a volume (as to the individual fre uencies) which corresponds to the volume of thel individual frequencies present naturally in speech and music. Stated in another form, this object is to royide a diaphragm which will oper- :ite without distort-ion inA the recording or reproduction of'speech and music.

The above and other objects of the iiiven-V tion areaccomplished by means of a diasound.

Application nied september 4, 192s.' semi No. 133,723.

Aphragin having various Zones adapted to respond to consecutive bands of frequencies extending from the very low to the very high frequencies present in speech and music.Y

AThe invention is disclosed in the forni of a all of the frequencies ofa certain band of' frequencies. This construction enables the diaphragm lo vibrate with a volume at practcally any frequency (in the voice or music j range) which corresponds with thevvolume of that frequency present in the natural A diaphragm having segments thereof of wedge-shape cross section will rcspond without appreciable distortion to music and speech and in accordance with the statutory requirements a circular form is being disclosed as the preferred form of the invention by way` of illustration but not in the limiting sense. Y

Fig. 1 is a plan view of one form of diaphragni.

k'F ig. 2 is a cross section on line 2 2 of Fig. l. Y

Fig. 3 lis a plan viewv of another form of diaphragm.

Fig. 4 is a cross section on line '1v-4 of Fig. 3.

Fi 5 ,is a plan view of a diaphragm having iaphragm zones of proportions differ-- ent from those shown in Fig. 3.

Fig. 6 is a cross section on line 6 6 vof Fig. 5.

Referring to Figs. 1 and 2, the diaphragm designated as a whole by 1,0 has a lower plane surface 11 and van upper plane sur-face 12. These two surfaces are other, as shown in Fig.,2, an each surface is a segment of a circle greater than a semicircumference. The Choi-dal boundaries of the two segments are illustrated as parallel to each other as shown in Fig. 1, .so that between the overlapping portions of the seg- A mental surfaces 11 and 12, there is formed a arallel to each On the under side of the disk is y 16. iThe base of the wedge is at the chordal boundary between segments 11 and 13 and the sharp edge of the wedge is at the periphery of the disk. Similarly, on lthe upper side of the disk there is a plane segmental surface 14 inclined to the siii-face 12 to form a second segmental diaphragm zone of 'wedge-shaped cross section 17.

'As showiLin both Figs. 1 and`2, the wedge shapedseg'mental diaphragm zone 1G is larger than tlfewedge shaped segmental zone 17, andffsrrice the .bases ofl both wedges are of the/saine thickness, the diaphragm zene 16 ismpre flexible than the zone 17. Accordingty, the zone 16 is adapted to respond in general to 'one band of frequencies while /the zone`17 is adapted to respond `in general to another band of frequencies, and the zone .l 15 to respond in general to-still another 20.*band of frequencies.

In F'gs.' 3 and 4, the diaphragm designated as a`whole by 418.' The ilnder surface 19 comprises a circular section of a single plane and the upper surface consists of two inclined segmental plane surfaces 20- and'22, which meet ata chordal boundary 21. The diaphragm has' its greatest thickness at the i chordal boundary 121 so that there is formed two segmental wedgeishaped diaphragm zones 23 and 24 separated by the chordal boundary21, which forms a ridge across the surface of the diaphragm. The diaphragm zone- 23 is more flexible than the zone 24j with the result that the zone 23 is in general 1 adapted .to respond tolow frequencies and the zonesl 24 to respond in general to medium `frequencies,while the highest frequenciesY are in general,.. handled bythat portion of the diaphragm contiguous to the ridge 21.

The dia hragmshown in Figs. 5 and 6 and desi ate as a whole by 25 is similar to the diap iragm of Figs. 3 and 4.v It consists of two segmental diaphragm zones 30 and 31 separated by a chordal ridge 27 and formed between the lower plane surface 26 and two segmental 'plane surfaces 28 and 29. The diaphragm of Figs. 5 .and 6 performs in much the same manner as the diaphragm of Figs. 3 and 4, but sincethe more flexible section '31 is larger in proportion than the more flexible section 23, the diaphragm of Figs. 5

and 6 is adapted to handle sounds which predominatev in low frequencies, e.v tain notes in organ music. I A

'I have found that diaphragms having wedge-shaped segmental zones will faithful- Iyhandle speech and music without appreciablev distortion. '.In some-types of music,

g., Cer- Alow frequencies predominate while-in others .in the positionsin which the width extending. chordall'y across the the upper and lower surfaces of the diaphragm referring only to the position of the surfaces as shown in the drawings. Of course, it is obvious that the diaphragm may beusedain any position and 'hence' the references to upper-'and lower are only for convenience in desi ating the surfaces diaphragms are shown inthe drawings.

It is realized that the invention may be embodied in-forms -other than' those par- :ticularly disclosed and hence the foregoing disclosure is to be considered as illustrative and not as limiting. Y A

Having thusdescribed my invention, what I claim is:

1. An acoustic diaphragm having two zones of wedge-shaped crosssection extendmg across the disk, and a zone of approx1- mately uniform thickness and uniform between the wedge-shaped zones.

2. An acoustic diaphragm having on each side a plane segment-shaped surface larger than a semicircle, the chordal `boundaries of the segments being parallel and\said plane surfaces being parallel; and two segment-shaped zones of wedge-shapedv cross section, said.zones being bounded' by said chordal boundaries and the peripheral edge of the disk.

3. An acoustic diaphragm comprising a plurality of vzones of wedge-sha ed'crosssection, and with the thickest portion of said cross section extending fromedge to edge of the diaphragm.

4. An acoustic diaphragm comprising two segmental zones of wedge-shaped cross section, one zone being larger than the other.

5. An acoustic diaphragm comprising a. pluralitY of wedge-shaped cross section portions o different sizes. extending across the diaphragm. f

6. A substantially disk-shaped acoustic diaphragm comprisingtwo segmental zones of wedge-shaped cross section, and a zone of substantially uniform thickness separating said wedge-shaped zones.

7. An acoustic diaphragm comprising a diaphragm zone formed byA two substantially plane surfaces onopposite faces of the diaphragm, the surfaces being opposite one another and at'an angle to each other to give the zone a wedge-shaped cross section, and with. the base of' said wedge-shaped vcross section extending across said diaphragm from edge to edge.

8. An acoustic diaphragm comprising a pluralit of diaphragm "zones, each zone being ormed by two substantially plane surfaces'on o posite faces of the diaphragm, the surfaces eing opposite one another and at an angle to each other to give the zones wedge-shaped cross sections, and with the greater portion of said zones being adjacent the thickest port'ion of the cross section.

9. An acoustic diaphragm comprising a plurality 'of diaphragm zones, the zones being of different sizesand each zone being formed by two substantially plane surfaces on opposite sides of -the diaphragm, the surfaces being opposite one another and at an angle to each other to give the zones Wedge-shaped cross sections.`

10. An acoustic diaphragm comprising two diaphragm zones, each zone being formed by. two substantially plane surfaces on 0pposite sides of the diaphragm, the surfaces being opposite one another and at an angle to each other to give the zones wedge-shaped cross sections, and with the thickest portion 0f said cross section extending across the diaphragm from edge to edge.

This specification signed this 3rd day of September, A. D. 1926. Y. Y CHARLES BLIEBERGER. 

